[MITgcm-support] how to modify the detail of model result
Ryan Abernathey
ryan.abernathey at gmail.com
Sat Jan 10 19:00:29 EST 2015
Tongya,
Perhaps you are expecting too much from MITgcm. In general, a free-running
model will never match the observed circulation as well as a
data-assimilating model such as HYCOM. This is especially true for high
resolution simulations such as the one you are running. These flows are
turbulent, so the most you can hope for is that the flow *statistics* (i.e.
mean velocities and eddy kinetic energies) match the observations. The
figures on your blog show qualitatively similar circulations for both
models.
If you would simply like the flow to be more "smooth," you can always just
turn up the viscosity. (This is what HYCOM does.) But keep in mind that
HYCOM is not the "true" ocean circulation either.
-Ryan
On Sat, Jan 10, 2015 at 7:26 AM, Tongya Liu <liutongya13 at mails.ucas.ac.cn>
wrote:
> Hi, Martin,
>
> Thank you for your reply. It's my fault that I didn't describe my problem
> clearly. I will share my other file below.
>
> The circulation of South China Sea is mainly controlled by the monsoon.
> Driven by the winter and summer monsoons, predominant basin-wide
> circulation in the upper layer is cyclonic and anticyclonic in the SCS,
> respectively.
>
> I show my result and HYCOM result of the monthly circulation in the
> website:
>
> http://blog.sina.com.cn/s/blog_7494b0230102va5m.html
>
> This is the model result of 7th years. I also use the KPP and EXF package.
> The flow of my case is in a mess, especially around the Luson
> strait and nearby the northern boundary. I don't know how to make the flow
> smooth.
>
> I know the open boundary is vital to the model result. I provide the u and
> v of monthly HYCOM data to the N,E,S boundary. To make the flow flux keep
> balance, I use the OBCS_balance. I have already modify the flow flux during
> preprocessing. You said in previous emails that if the boundary have strong
> inflow or outflow, the OBCS_balanceFac* should be 0. In my case, there are
> NEC and Kuroshio in the N and E boundary. The southern boundary will
> directly influence the South China Sea Western Boundary(SCSWB), which is
> important in the circulation of SCS. What the OBCS_balanceFac* should be
> set? I have tried to use the orlanski and Sponge Layer, but the result is
> not good.
>
> Please give me some advices. Thank you very much.
>
> Tongya Liu
>
> data file:
>
> # ====================
> # | Model parameters |
> # ====================
> #
> # Continuous equation parameters
> &PARM01
> viscAr=1.77E-3,
> viscAh=0,
> diffKhT=0,
> diffKrT=1.51E-5,
> diffKhS=0,
> diffKrS=1.51E-5,
> useFullLeith=.TRUE.,
> viscC4Leith=1.0,
> viscC4Leithd=1.0,
> viscA4GridMax=1.0,
>
> tempAdvScheme=33,
> saltAdvScheme=33,
> eosType = 'JMD95Z',
>
> no_slip_sides=.FALSE.,
> no_slip_bottom=.TRUE.,
> bottomDragQuadratic=0.0025,
> implicitDiffusion=.TRUE.,
> implicitFreeSurface=.TRUE.,
> implicitViscosity=.TRUE.,
>
> staggerTimeStep=.TRUE.,
> implicitFreeSurface=.TRUE.,
> exactConserv=.TRUE.,
> hFacMin=0.1,
> readBinaryPrec=64,
> #- not safe to use globalFiles in multi-processors runs
> globalFiles=.TRUE.,
> useSingleCpuIO=.TRUE.,
> &
>
> # Elliptic solver parameters
> &PARM02
> cg2dMaxIters=1000,
> cg2dTargetResidual=1.E-13,
> &
>
> # Time stepping parameters
> &PARM03
> nIter0= 0,
> #nIter0= 34560,
> nTimeSteps = 2592000,
> #startTime=0.,
> #endTime=311040000.,
> basetime=0,
> deltaT=1200.0,
> abEps=0.1,
> momDissip_In_AB=.FALSE.,
> dumpFreq=864000.0,
> pChkptFreq=31104000.,
> chkptFreq=2592000.,
> monitorSelect=2,
> monitorFreq=1200.,
>
> &
>
> # Gridding parameters
> &PARM04
> usingSphericalPolarGrid=.TRUE.,
> ygOrigin=0.0,
> xgOrigin=99.,
> dxSpacing=0.1,
> dySpacing=0.1,
> delR=30.,30.,30.,30.,30.,30.,
> 30.,30.,30.,30.,30.,30.,
> 30.,30.,30.,30.,30.,30.,
> 30.,30.,50.,50.,100.,200.,
> 300.,500.,600.,800.,800.,1000.,
> &
> # Input datasets
> &PARM05
> bathyFile='topog.bin',
> hydrogThetaFile='Temp.bin',
> hydrogSaltFile='Salt.bin',
> &
>
> data.obcs:
> &OBCS_PARM01
>
> OBCSfixTopo=.FALSE.,
> OB_Jnorth= 360*-1,
> OB_Jsouth= 360*1,
> OB_Ieast = 300*-1,
>
> useOBCSprescribe = .TRUE.,
> useOrlanskiNorth = .TRUE.,
> useOrlanskiSouth = .TRUE.,
> useOrlanskiEast = .TRUE.,
>
> useOBCSbalance=.TRUE.,
> OBCS_balanceFacN= 0.,
> OBCS_balanceFacS= 1.,
> OBCS_balanceFacE= 1.,
>
> OBNuFile = 'OB_NorthU.bin',
> OBSuFile = 'OB_SouthU.bin',
> OBEuFile = 'OB_EastU.bin',
> OBNvFile = 'OB_NorthV.bin',
> OBSvFile = 'OB_SouthV.bin',
> OBEvFile = 'OB_EastV.bin',
>
> OBNsFile = 'snorth.bin',
> OBNtFile = 'tnorth.bin',
> OBEsFile = 'seast.bin',
> OBEtFile = 'teast.bin',
> OBSsFile = 'ssouth.bin',
> OBStFile = 'tsouth.bin',
>
> OBCS_monitorFreq= 3600.,
> OBCS_monSelect = 1,
> &
>
> # Orlanski parameters
> &OBCS_PARM02
> Cmax=0.45,
> cVelTimeScale=1000.,
> &
>
> data.kpp:
> # KPP parameters
> &KPP_PARM01
> KPPmixingMaps = .FALSE.,
> KPPwriteState = .TRUE.,
> KPP_ghatUseTotalDiffus=.TRUE.,
> &
>
> data.exf
> # *********************
> # External Forcing Data
> # *********************
> &EXF_NML_01
> repeatPeriod= 31104000.,
> readStressOnCgrid = .TRUE.,
> exf_iprec = 64,
> useExfCheckRange =.TRUE.,
> &
>
> # *********************
> &EXF_NML_02
> #hfluxstartdate1 = 00000101,
> #hfluxstartdate2 = 000000,
> #hfluxperiod = 2592000.0,
> #
> #sfluxstartdate1 = 00000101,
> #sfluxstartdate2 = 000000,
> #sfluxperiod = 2592000.0,
> #
> ustressstartdate1 = 00000101,
> ustressstartdate2 = 000000,
> ustressperiod = 2592000.0,
> #
> vstressstartdate1 = 00000101,
> vstressstartdate2 = 000000,
> vstressperiod = 2592000.0,
> #
> climsststartdate1 = 00010101,
> climsststartdate2 = 000000,
> climsstperiod = 2592000.0,
> # 1 day restoring timescale for temperature
> climsstTauRelax = 86400.,
> #
> climsssstartdate1 = 00010101,
> climsssstartdate2 = 000000,
> climsssperiod = 2592000.0,
> # 1 day restoring timescale for salinity
> climsssTauRelax = 86400.,
> #
> #hfluxfile = 'hflux.bin',
> #sfluxfile = 'ncep_emp.bin',
> #uwindfile = 'uwind.bin',
> #vwindfile = 'vwind.bin',
> climsstfile = 'sst.bin',
> climsssfile = 'sss.bin',
> ustressfile = 'tx.bin',
> vstressfile = 'ty.bin',
> #
> &
>
> # *********************
> &EXF_NML_03
> &
>
> # *********************
> &EXF_NML_04
>
> &
> &EXF_NML_OBCS
> obcsEstartdate1 = 00000101,
> obcsEstartdate2 = 00000,
> obcsEperiod = 2592000,
> #
> obcsNstartdate1 = 00000101,
> obcsNstartdate2 = 000000,
> obcsNperiod = 2592000,
> #
> obcsSstartdate1 = 00000101,
> obcsSstartdate2 = 000000,
> obcsSperiod = 2592000,
> &
>
>
>
>
>
> _______________________________________________
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> MITgcm-support at mitgcm.org
> http://mitgcm.org/mailman/listinfo/mitgcm-support
>
>
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